Counterbalancing means for punch press



5 Shets-Sheet 1 NWN I Oct. 8, 1957 P. s. JACKSON COUNTERBALANCING MEANSFOR PUNCH PRESS Filed Feb. 7, 952

INVEN TOR. ad 5. JQCk-SOJZ; M

0c; 8, 1957 P. s. JACKSON 2,808,736

COUNTERBALANCINGMEANS FOR PUNCH PRESS Filed Feb. 7, 1952 5 Sheets-Sheet2 Y BY 1957 I P. s. JACKSON 2,808,736

COUNTERBALANCING MEANS FOR PUNCH PRESS Filed Feb. '7, 1952 5Sheets-Sheet 4 I INVEQTORVU 1957 P. s. JACKSON 2,808,736

I COUNTERBALANCING MEANS FOR PUNCHPRESS I Filed Feb. 7, 1952 5Sheets-Sheet 5 INVENTOR.

4 ml \9. dc zciaom COUNTERBALANCENG MEANS FOR PUNCH PRESS Paul S.Jackson, Rockford, 111., assignor to Jackson Hydraulic Machine Co. Inc,a corporation of Eiliuois Application February 7, 1952, Serial No.270,377

Claims. (Cl. 74604) This invention relates to a method and apparatus forcounterbalancing a reciprocating force and to a punch pressincorporating such counterbalancing means together with means foradjusting the die of the press toward and away from the ram and forfeeding a workpiece between the ram and the die.

It is the general object of this invention to produce new and improvedapparatus and methods as described in the preceding paragraph.

It is well known that a reciprocating mass produces a primary unbalancein the plane of reciprocation of the mass. In a vertical punch press forexample, maximum upward unbalance is manifested as the crankshaft passesover top dead center and maximum downward unbalance occurs when thecrankshaft passes over bottom dead center. With a reciprocating mass twoneutral points exist, which points are approximately 90 between top andbottom dead centers.

It is possible to counterbalance a portion 'of the primary unbalance bycounterweights. A common procedure which has been followed is tocounterbalance half the weight of the reciprocating mass by attaching aweight to the crankshaft opposite to the crankpin with the weight havingan inertia equal to half the inertia of the reciproeating parts.Rotation of the counterbalance weight serves to offset or diminish theprimary unbalance of the reciprocating mass by about fifty percentinasmuch as the counterbalance is maintained oppositely to the mass andhence passes over top dead center as the mass passes over bottom deadcenter. Because of the fact that in such systems the counterbalanceweight is rotating rather than reciprocating, transverse unbalanceforces are introduced into the system at points approximately 90 fromdead center. As just noted, maximum reduction of vibration is attainedin such systems by constructing the counterbalance Weight so that it hasan inertia equal to onehalf of the inertia of the reciprocating parts,that is, the Weight of the counterbalance weight multiplied by itsdistance from its axis of rotation should be equal to approximatelyone-half of the mass of the reciprocating parts multiplied by the throwof the crank to which it is connected. With the counterbalance weight soconstructed it Offsets approximately 50% of the primary unbalance but,as noted, introduces transverse unbalance of approximately equalintensity. If the counterbalance weight is constructed to counterbalancemore'than half of the primary unbalance, then the transverse unbalancebecomes greater than the primary unbalance and little benefit isachieved. The transverse unbalance is of course exerted in a planesubstantially normal to the plane of reciprocation of the reciprocatingmass and thus .in a vertical punch press, for example, the transverseunbalance is exerted in a horizontal plane.

It is one of the features of the present invention to provide a methodand an apparatus whereby the total amount of primary unbalance mayeffectually be canceled out by using a plurality of rotatingcounterbalance weights 2,808,73fi Patented Oct. 8, 1957 but which are soconstructed as to also eliminate transverse unbalance. To this end thereis provided a plurality of counterbalance weights which are rotated inunison with the reciprocation of the mass so as to pass over top deadcenter when the mass passes over bottom dead center with the sum of theinertias of the counterbalance weights being equal to the inertia of thereciprocating mass. Thus, the counterbalancing weights cancel outsubstantially all of the primary unbalance of the system. Thecounterbalance weights themselves are so rotated as to be in spacedrelationship to each other in a plane normal to the plane ofreciprocation of the mass so that the transverse unbalance of eachweight opposes a transverse unbalance of another weight so that suchtransverse unbalance forces are canceled out. A simple form ofconstruction would include a pair of counterbalance weights which arerotated in unison with the rewhich serve not only to eliminate primaryunbalance, i

ciprocation of the reciprocating mass and so arranged that the weightspass over top dead center as the mass passes over bottom dead center andwith the weights rotating in opposite directions and in the same planeso that at the'points from dead center the transverse unbalance force ofone weight is exerted in one direction while an equal transverseunbalance force created by the other weight is exerted in the oppositedirection, thus permitting the two equal but opposed transverseunbalance forces to cancel each other out.

Where a reciprocating mass, such as the ram of a punch press, isreciprocated by a crankshaft and connecting rod arrangement, a furtherunbalance'fac'tor arises because of the fact that when a crankshaft withits connected reciprocated weight and connecting rod passes over bottomdead center position (where the weight is below the crankshaft), thecrank throw length is added to the connecting rod length in calculatingthe inertia force or the massmoment, while on the other hand in passingover top'dead center position the crank throw length is subtracted fromthe connecting rod length resulting in a lesser unbalanced force. Thisform of unbalance is known as secondary unbalance.

In order to eliminate secondary unbalance, I prefer to dispense with aconnecting rod and in its place use a slotted crosshead (or scotch yokeprinciple). This method of drive produces a simple harmonic motion ofthe reciprocating parts with the result that. the massmoments of thereciprocating mass are equal both in the top dead center position and inthe bottom dead center position. The use of the slotted crosshead givesthe same results as if using a connecting rod having a length ofinfinity. Thus, the length of the crank throw does not vary the inertiaforces between top and bottom dead centers.

In the event that the counterbalancing method and apparatus hereindisclosed is employed on a punch press which is equipped with a ramwhose weight may vary depending upon the type and number of punchessecured thereto, as a further feature of the invention I providecounterweights which are readily removable and replaceable by othercounterweights of different mass so that a ready correlation between themass of the counterweights and that of the reciprocating ram can beeffected. As a further feature of the invention I may providecounterweights which are adjustable so that it is not necessary toremove the weights but merely to shift their position rela- 3 weight ofthe counterbalance weight itself may be reduced while achieving the sameinertia forces for the counterbalancing system.

.It is usually required in a punch press to provide some means ofadjusting the position of the punches in the ram relative to the diemounted on the bolster or press frame below. This adjustment normallyrequires the use of one or more heavy adjusting screws and a lockingdevice mounted on the ram. Inasmuch as the punch press disclosed hereinis designed for heavy duty, high speed operation, it is desirable toreduce the weight of the ram as much as possible so as to reduce theover-all required weight of the press including the counterbalancesystem. As an additional feature of the invention, I provide a movabledie holder on the frame of the press which is adapted to be moved by theadjusting screws and. to be held in adjusted position by lockingdevices. Thus, the necessary adjustment of the relationship between theram and the die is achieved not by means mounted on the ram, as hasheretofore been the practice,vbut. rather by means mounted on the frameapart from the ram.

Another feature of the invention is the provision in a die adjustingmechanism of the type mentioned in the preceding paragraph of aplurality of adjusting screws which may be motor driven so as rapidly toeffect the raising and lowering of the die relative .to .the ramtogether With an easily operated locking mechanism which serves to lockthe screws in adjusted position.

Yet another feature of the invention is the provision of a novel feedmeans for feeding a workpiece between the die and ram of a punch presswhich is operable either to move a workpiece at a feed rate orat a rapidrate so that a series of punches may be formed on a workpiece, with eachseries being spaced a predetermined amount. 'During the formation ofeach series of punches, the workpiece is moved at a feed rate to spacethe punch holes a predetermined amount, while the workpiece is moved ata rapid rate between each series of punches so as to space the seriesfrom one another along the length of the workpiece. Thus, the spacingcan be achieved Without slowing the ram or press.

Another feature of the invention is to mount the feed rolls which serveas a part of the feed mechanism just described on the movable die holderso that adjustment of the die holder relative to the ram does not affectthe relationship between the feed rollers and the die.

Yet another feature of the invention is the provision of a feed meansconnected directly to one of the crossheads in a punch press or othermachine of that general type so that the sliding movement of thecrosshead produces oscillation of the feed mechanism. Thus, a feed canbe achieved without the use of independently rotated cams and the like.

Other and further features and objects of the invention will be readilyapparent from the following description and drawings, in which: a

Fig. 1 is a top plan View of a punch press embodying the feature of theinvention;

Fig. 2 is a side elevation of the upper portion of the press, partiallybroken away for clarity of illustration, taken on line 2-2 of Fig. 1;

Fig. 3 is a front elevational view of the lower portion of the pressshowing a part of the feed mechanism and the means for adjusting thedie;

Fig. 4 is a vertical sectional view of the press taken along line 4-4 ofFigs. 2 and 3; and

Fig. 5 is a horizontal sectional view through the upper portion of thepress taken along line 5--5 of Fig. .2.

While this invention is susceptible of embodiments in many differentforms, there is shown in the drawings and will herein be described indetail one specific embodiment, with the understanding that the presentdisclosure is to be considered as an exemplifieation of the principlesof the invention and is not intended to limit theinvention to theembodiment illustrated. Thescope of the invention will be pointed out inthe appended claims.

Referring now to Fig. 4, the apparatus of this inven-..

tion is shown as incorporated. in a punch press including a frame Awhich supports at its top a driving mechanism B for driving thecrankshaft system C of the press. The crankshaft system is connected toa ram D for reciprocating the same toward and away from the die E of thepress, with the die being supported on an adjusting system F.

The frame includes a pair of vertical steel panels or side plates 10 and11 which carries the mechanism of the press and which are provided withaligned openings 12 and 13 through which a workpiece is passed throughand beneath the ram of the press. Supported at the top of the sideplates is a pair of spaced horizontal top plates 1414a which carry anelectric motor 15 for driving the press through the medium of a pulley16 secured to the drive shaft of the motor which carries a plurality ofV-belts 17 engaging a second pulley 18 secured to one of the driveshafts 19 of the press. As best shown in Fig. 1, the top of the ramcarries a plurality of oil lines 20' which serve to lubricate variousportions of the press, as will hereinafter be described. A transparentplastic cover 14b is secured to the top plates and extends over thespace therebetween to prevent oil from splashing upwardly as the ram isreciprocated.

Referring now to Fig. 5, parallel to and horizontally spaced from thecrankshaft 19 is a second crankshaft 21, with both crankshafts beingrotatably mounted on relatively massive, anti-friction bearings 22carried by the side plates of the frame. Each of the bearings is mountedon a. conical-shaped removable sleeve 23 machined properly to fit theouter surface of the crankshaft and the inside of the inner bearing raceof each of the bearings 22. Fixed to the crankshaft 19 adjacent the endsthereof is a pair of gears 24 and 25 which mesh with a similar pair ofgears 26 and 27 secured to the crankshaft 21. The gears are in a 1 to 1ratio so that rotation of the shaft 19 in one direction throughthemedium of the driving pulley 18 rotates the shaft 21 at the same speedbut in the opposite direction. The gears are each mounted on removalsleeves 28 and spaced from the bearings 22 by spacers 30a. The removalsleeves 28 are held in position by nuts 29 which, after being tightenedin position, are held against slippage by keyed lockwashers 30.

Integrally formed on each of the cranksh afts 19 and 21 is taperedeccentrics 31 and 32. The eccentrics are oppositely positioned so asboth to be facing toward the center line of the press in one positionand horizontally outward from the center line when rotated 180, with theeccentrics being in aligned relationship in vertical planes so as toachieve the reciprocation of the ram.

As previously noted, the eccentrics ,31 and 32 are tapered toward eachend with the oppositely facing tapers on each eccentric being separatedby integral rings 33 and 34 which act as spacers for pairs ofanti-friction bearings 35 and 35a and 36 and 36a carried by theeccentrics 31 and 32 respectively. It will be noted that the innersurface of the bearing races of each of the anti-friction bearings insaid pairs is tapered to facilitate press-fitting the pairs of hearingson the eccentrics. To provide for easy removal of the bearings whentheir replacement becomes necessary, each crankshaft is drilled asindicated at 37 to form an oil passage communicating with an annular oilgroove 38 formed on each taper of each eccentric. Introduction of oilunder pressure into the passages 37 and thence to the passages 38spreads the inner side of the bearing races slightly but sufliciently topermit the bearings to be removed with ease.

Inasmuch as the drive shafts 19 and 21 are not symmetrical but ratherare provided with off-center eccentrics, the drive shafts themselveswould produce unbalrance forces when rotated. To elf-set the unbalanceof the crankshafts which is equal both at top and bottom dead center,each of the gears 2427 is provided with drilled openings 40 positionedon the same side of the nuts 49 to maintain the frame in place.

crankshaft as the eccentricity of the eccentrics and serves to off-setany unbalance produced by such eccentrics. The holes 40 may, if desired,be of a size suflicient only to counterbalance the eccentrics. Ifdesired, the holes may be larger than necessary to counterbalance theeccentrics to further reduce the weight of the counterbalancingmechanism for the entire press. For counterbalancing the ram which isreciprocated by the crankshafts, each of the gears 2427 is provided withcounterbalance weights 4144 positioned oppositely from the holes 40 withthe weights being removably held in a groove formed in the gear by thescrew device illustrated. Counterbalance weight of diiferent mass may berequired depending upon the weight of the ram and punch assembly; and aspunches are changed, which naturally results in a change in the weightof the ram, the counterbalance weights may also be changed. Aspreviously mentioned, the weights may be adjustably fixed on the gears,such as by mounting them on eccentric shafts, so that the weights may bemoved inwardly toward or outwardly away from the axis of rotation of thecrankshafts to increase or decrease the inertia of the weights and thusto adjust for varying ram weights.

From the foregoing it will be evident that the gears 2427 serve not onlyas driving members to drive the crankshaft 21 at the same speed but inthe opposite direction to the rotation of the shaft 19, but also serveas counterbalance weights not only for the eccentrics, as has just beendescribed, but also for the reciprocating parts hereinafter to bedescribed. It will be further noted that the counterbalance weights onthe gears are oppositely positioned in a plane normal to the plane ofreciprocation of the ram. Thus, when the gears are in the position shownin Fig. 5, the counterbalance weights 41 and 42 exert an outward force(to the left as shown in that figure) while the counterbalance weights43 land 44, being equal in mass to the weights 41 and 42, exert an equalbut opposite outward force (to the right as seen in Fig. 5). When thecrankshafts have been rotated 90 from the position shown in Fig. 5, allof the counterweights will be exerting an accumulative force in avertical plane, that is in the plane of reciprocation of the ram, andwhen the crankshafts have further been rotated an additional 90, thecounterweights will be exerting opposite but equal inward forces. By sopositioning and rotating the counterweights on the two parallelcrankshafts, transverse unbalance created by any one counterweight isoifset by an equal and opposite transverse unbalance of anothercounterweight. Thus, the counterweights are mounted so as to be inopposing relationship, that is opposed to another counterweight inplanes normal to the plane of reciprocation of the ram but are mountedto be in accumulative relationship in the plane of reciprocation of theram. Inasmuch as the counterweights pass over top dead center as the rampasses over bottom dead center, the accumulative force of thecounterweights is opposite to the unbalance force exerted by the ram andwith proper proportioning of the counterweights may be made equal to theunbalance force of the ram. The counterweights, by their accumulativeeffect, therefore, quite effectively counterbalance the primaryunbalance forces of the ram.

As previously mentioned, slotted crossheads or scotch yokes are employedfor translating the rotary movement of the eccentrics into reciprocalmovement of the ram. To this end each pair of bearings 35 and 35a and 36and 36a is mounted in a crosshead slidable in suitable ways formed in acrosshead way frame. The crosshead way frame includes an upper plate inthe form of a channel member 45 and a lower member 46. The members aremaintained in spaced parallel relationship by aluminum spacer blocks47a, 47b and 47c. Bolts 48 pass through the members and blocks and areprovided with suitable I Upper and lower bronze bearing plates 50 and 51are secured to the inner sides of the members 45 and 46 to provide slidebearings for a pair of crossheads 52 and 53 which in turn are carried bythe bearings 35 and 35a, and 36 and 36a. Thus, movement of theeccentrics in a horizontal plane produces merely sliding movementbetween the crossheads and their ways while movement in vertical planescauses vertical movement of the crossheads and ways. The actual movementof the crossheads is circular but relative to the ways is a horizontalmovement back and forth.

Secured to the center spacer block 4712 is a pair of V-gibs 56 whichextends vertically from top to bottom of .the crosshead way frame andare slidable in suitably formed bearing surfaces 57 which are secured tothe frame and extend vertically therealong. End gibs 58a and 580 aresecured to the end spacer blocks 47a and 470 and are slidable onsuitable bearing surfaces 59a and 59c also secured to the framework soasto provide a guided support means for the reciprocating parts of thepress. 'The V construction of the center gibs makes an accurate centerguide for the ram and still permits it to expand equally toboth endsfrom the center.

Lubrication of the crossheads in their ways is supplied through thelubricating conduits 20 previously noted. For the purpose of circulatingthe lubricating fluid, each of the spacer'blocks 47a47c is provided witha lube oil passages 60a-60c. Oil is introduced into suitableinterconnected lubricating grooves formed in the bearing sur faces 50and 51 through a lube oil connection 61 in turn connected to one of theoil lines 20. Lubricating oil in the grooves on the bearing surfacespasses outwardly from the connectionof the line 61 thereto andcirculates, by means of the spacer block passages 60a-60c, throughsimilar lube oil grooves formed in the lower crosshead bearing surface.A suitable drain connection is provided for the lower bearing surface 51to produce a continuous circulation of lubricating oil for, thecrosshead way system.

The ram D comprises a welded steel arm 62 secured at its upper end tothe lower crosshead way frame member I 46 and provided at its lower endwith means for securing thereto a punch holder 63, a punch liner 64 andupper and lower wedges 65. The punch holder, punch liner and upper andlower wedges are held in position on the arm 62 by clamps 66. A stripperplate 67 is carried by upper clamps 68 secured to side rails 69 fixed inthe frame.

It will be noted that the ram assembly does not include the usualadjusting screws for adjusting the punches mounted on the punch holderrelative to the die of the press. Thus, the weight of the ram is reducedto a minimum without in any manner detracting from, and in fact addingto, its strength.

The reciprocating ram of the press and its attendant accessories issubstantially completely counterbalanced by the counterbalance weightsattached to the gears hereinbefore described. It will be noted that theweights are located symmetrically about the center line of thereciprocating mass, that is are positioned equidistantly on both sidesof such center line and symmetrically front and rear. Because of thissymmetrical relationship of the counterbalance weight, no rocking coupleis introduced in the system and the weights, when acting in accumulativerelationship, counterbalance the primary unbalance of the reciprocatingram and are in opposed relationship from between top and bottom deadcenter of the ram (where the ram creates no primary unbalance)effectively to cancel out the transverse unbalance of the rotatingweights. In the specific embodiment shown, the press is a one hundredton punch press, the ram weighs about nine hundred pounds and theeccentrics have a quarter inch throw and thus impart a half inch stroketo the ram. Thus, the ram develops an inertia of two hundred twenty-fiveinch pounds. The counterbalance weights are aboutfive and a half inchesfrom their axes of rotation and, as four are provided, each balances onefourth themass-moment of the ram, thus each weighs about ten pounds.With the' press so counterbalanced, speeds up to five hundred strokesper minute have been achieved without creating vibrations suificient totip a coin balanced on edge on'the press frame.

The die assembly E comprises a die holder 70 having a suitable grooveinwhich there is located a die shoe 71 which carries a suitably formed die72. Positioned on either side of the die are lower guides 73. The dieholder 70 is clamped toa bottom plate 74 by a die clamp 75 and thebottom plate is bolted to a base plate or platen '76 movably mounted inthe frame A. As previously noted, the die assembly E is providedwith anadjusting means F for adjusting the die relative to the punches in thepunch holder with the adjusting means being mounted on the frame ratherthan carried by the ram.

Theadjusting means F are so designed as to facilitate vertical movementof the die on the frame properly to position it relative to the ram andalso to permit rapid replacement of broken punches and the like. Theadjusting mea'ns F is provided with a plurality of screws 80 havingexternal threads engaging the threads of an internally threaded collar81 fixed to a lower cross brace 82 in the frame. A housing '83 is fixedto the lower side of the platen 76 and encloses a transversely extendingdrive shaft 84 carrying a plurality of worms 85 each engaging a wormrear 86 fixed to the leadjscrews 80. Thus, each of the screws 80'isprovided with a worm gear 86 affixed thereto so that rotation of thescrews and hence vertical movement of the platen may be achieved byrotating the shaft 84. If desired, a motor may be attached to the shaft85, which motor may be operated by a suitable manual or pedal control toachieve rotation in either direction of the shaft 84 and hence toraise'or lower the platen, and thus the die, toward'and away from theram. It will be noted that the upper face of the worm gear 86 bearsagainst a face portion 87 of the housing 83 and by movement thereagainstwith rotation of the screw accomplishes vertical movement of the platen.

It is necessary after making an adjustment of the die relative to theram, that is after rotating the adjusting screws 80, that the screwsbelocked in adjusted position to prevent creeping during the operationof the'press. To this end one or more of the lead screws are hollow andprovided with locking means to prevent such creeping movement. In theexemplary embodiment of the invention shown, three of the screws 80 areso constructed,

thus as seen in Fig. 4, wherein one of such hollow screws isillustrated, there is provided a locking rod 90 secured by means of thekey 91 in a hollow 92 formed in the lead screw 80. The keyed connectionbetween the screw and the locking rod is such as to prevent relativerotation between the screw and the rod but to permit slidinglongitudinal movement between the rod and the screw. The lower end ofthe locking rod is threaded at 93 with the threads having the same pitchas the threads formed on the exterior surface of the lead screws 80 andwith the threads 93 engaging threads formed in the interior of a wormgear 94. A worm 95 fixed to a rotatable shaft 96 engages the teeth ofthe gear 94 so that rotation of the shaft 96 causes rotation of the wormgear 94. The upper end 97 of the rod is provided with a collar 98 to'hold the rod in position with the lower face of the collar being adaptedto bear against the upper portion of the bottom plate 74. A foot treadle99 (Fig. 3) is provided for rotating the shaft 96 and hence to rotateall of the worm gears 94. Inasmuch as the threads formed at the lowerend of the locking rod have the same pitch as the threads on the leadscrew and as the key-way 91 causes the screw and rod to rotate together,vertical adjustment of the platen may be achieved through rotation ofthe shaft 84.

The similar pitch of the threads in the rod and screw permits suchrotational movement Without'corresponding as... rotation of the wormgear 94. When the platen has been moved to the desired position, it ismerely necessary for the operator to step on the treadle99 to causerotation of the shaft 96 and hence of the worm gears 94, Such movementserves to move the rod 93 downwardly to bring the lower face of thecollar against the upper face of the b ottom plate and thus to applysufficient tension on the lead screw and'rod as to prevent theirrotating with operation of the press. To release the adjusting means forfurther adjustment, it is merely necessary to rotate the shaft 96 in theopposite direction, thus releasing the locking means.

Means are provided on the press for feeding a workpiece in predeterminedincrements to the ram and die during the. reciprocation of the ram. Forthis purpose there is mounted on the platen.7.6 twopairs-of feed rolls193-101 and 100a 101a with the rolls in each pair being verticallyarranged and with the pairs being located on opposite sides of the die.,The rolls are rotatably mounted on the platen, for example as shown inFig. '3 the lower rolls 100100a and upper rolls 101-101a are suitablyjournaled in bearings 102-102a and 103 103a at each end. Secured to theshaft carrying each of the rolls is an upperdrive gear 104 and a lowerdrive gear 105. Thefrolls are pressed together by pneumatic piston andcylinder devices 106 mounted at each end of the upper roll and means areprovided for operating such devices to separate the rolls slightly topermit insertion of a workpiece in the nip between the rolls. The teethon the gears 104 and are made extra long so that they remain in mesh inall positions of the upper roll relative to the lower roll. If desired,a lubricant may be supplied to the workpiece by the upper T011 101 andto this end it may be provided with a hollow shaft connected to asuitable lube line 108 which feeds lubricant into the interior of the.upper roll from which it is extruded through small openings 109 in thesurface of the roll and onto the surface of the workpiece The lower roll100 rotates in a pan 110 of lubricant to supply its surface with oil. 7

A friction clutch, such as the clutch 111, is provided for the lowerroll of each pair and is-so designed as to prevent rotation of the rollsexcept through the positive action of feed means hereinafter to bedescribed. Thus, when the rolls arestationary, the workpiece heldtherein is maintained in fixed relationship relative to the ram and dieand backlash or slippage of the rolls and hence of the workpiece isprevented.

The feed rollers 100 and 101 are located at the entering side of theworkpiece while the opposite pair of feed rolls 100a and 101a is at theexit side. The upper roll 101:: of the exit feed rolls may also beprovided with pneumatic devices 112 for raising and lowering the upperroll relative to the lower roll 100a for the purpose of permitting theinitial insertion of a workpiece.

Means are provided for rotating both pairs of feed rolls in unison andby predetermined increments to feed a workpiece through the press. Toprovide for such intermittent movement of the feed rolls there isprovided a rod (Fig. 2) threaded into the crosshead 5 2 and pivotallyconnected to a second rod 121in turn connected by a link 122 to a shaft123' rotatably mounted in the frame. The shaft carries a block 124provided with a dovetailed groove 125 in which is slidably mounted ablock 126 rotatably carrying anactuating rod 127. With operation of thepress the rotary movement (relative to the fixed frame) of the crosshead52 is imparted to the rod 120 and translated by the link 122 intooscillatory movement of the shaft 123 and hence pivotal rocking movementof the block 124. The slide block 126 may be secured in the groove 125at any desired position away from the axis of rotation of the block soas to impart to the actuating rod 127 whatever degree of verticalreciprocation is desired, ranging from zero, when its pivotalconnectionto the slide block coincides with the axis of movement of theblock 24, to maximum when the block is adjacent the end of thedovetailed groove,

The actuating rod 127 is connected at its lower end to a verticallyreciprocable member 128 having rack teeth thereon engaging teeth 129 ona gear 130 fixed to a clutch shaft 131 having one end journaled in apillow block 132 fixed to the platen, and having its other end supportedin a free-wheeling indexing type clutch 133. The clutch 133 is of wellknown construction adapted to impart to the drive gear 105 motion in onedirection only in response to the oscillatory movement. of the shaft131.

The gears 104 and 105 are connected through a gear train (not shown) tosimilar gears connected to the top and bottom rollers of the other pairof feed rollers so that both pairs of feed rollers are simultaneouslydriven. The gear corresponding to the gear 105 secured to the roll 100ais connected through a second freewheeling indexing type clutch, clutchshaft, gear and rack to the piston of an air cylinder 134 which isadapted, when air under pressure is introduced into the cylinder, torotate both pairs of feed rollers rapidly to advance a workpiece throughthe press.

The gear 130 may be shifted along the shaft 131 t disengage its teethfrom those of the rack 129. To this end there is provided a hand lever135 provided at 136 to the frame and secured to a pair of verticallyspaced arms 137 and 137a each carrying detents 138 and 138a which ridein an annular groove 139 formed in the gear 130. Movement of the handle135 slides the gear teeth out of mesh with the rack teeth to disconnectthe feed mechanism.

If a series of perforations are to be made in a workpiece, for examplethe perforations in the back panel of a radio or television set, a longworkpiece may be inserted in the rolls and the press started. Eachstroke of the ram punches one row of holes in the workpiece and on eachstroke the feed mechanism serves to rotate both pairs of feed rolls andadvance the workpice slightly to determine the spacing betweenperforations. When the required number of rows of perforations has beenpunched in the workpiece, the air cylinder 134 is operated, eithermanually or by suitable automatic controls, rapidly to rotate both pairsof feed rollers a distance greater than their rotation during the feedoperation and thus to provide a space between the first series ofperforations and a succeeding series. Both feed and rapid speedmechanism operate while the punches are out of contact with theworkpiece, that is they ,operate when the ram is moving upwardly towardtop dead center and during only a portion of the rams movementdownwardly toward the die and workpiece. To prevent operation of the aircylinder when the punches are in contact with the workpiece, a suitablelimit switch may be incorporated in the electrical energizing means forthe air cylinder valve to permit such energization only when the ram isnear top dead center.

It will be noted that the feed rolls and most of the feed mechanism iscarried by the platen and thus adjustments of the platen upwardly ordownwardly do not misalign the feed rolls. If desired, the feed rollsmay be provided with an individual adjustment to lower the position ofthe lower rolls as the dies are reground, thus making it a simple matterto keep the top of the lower roll of each pair in the same plane as thereground die. A similar adjustment is not necessary for the upper rollsinasmuch as the air cylinders with which each of the upper rolls isprovided serves to move those rolls down wardly against its associatedlower roll.

The die holder 70 is provided with openings at the location of the dieso that the small portions of the workpiece which are punched out by thepunches drop therethrough onto a waste conveyor belt 140 suitablymounted on rollers 141, one of which 141a is driven by a motor 142. Thebelt is driven in the direction indicated by the arrow so that the wasteslugs are carried on the were uppensurface of the belt toward a chute143 positioned at theleft-hand side of the press (as seen in Fig. 3) andas the belt passes around the first roller 141, such slugs drop off intothe waste chute.

I claim:

1. Apparatus of the character described comprising a support, a pair ofspaced parallel crankshafts rotatably mounted on the support, a massmounted for reciprocation on the support along a path lying between saidcrankshafts and approximately normal to a plane' passing through theaxes of said crankshafts, means connecting the mass to the crankshafts,means for rotating the crankshafts to reciprocate the mass, a first pairof counterbalance weights of equal mass mounted for rotation in parallelplanes substantially parallel to the path of reciprocation of the massat the opposite ends of one crankshaft, a second pair of counterbalanceweights of equal mass mounted for rotation in said planes at theopposite ends of the other crankshaft, each pair of weights beingarranged to .be in oppose relationship to the other pair in a planenormal to said path and to be in accumulative relationship and opposedto the mass in a plane paralleling said path.

2. Apparatus of the character described comprising a support, a pair ofspaced parallel crankshafts rotatably mounted on the support, a massmounted for reciprocation on the support along a path lying between saidcrankshafts and approximately normal to a plane passing through the axesof said crankshafts, means connecting the mass to the crankshafts, afirst pair of gears mounted in spaced relationship on one of thecrankshafts, each meshing with one of a similar pair of gears mounted onthe other crankshaft whereby said crankshafts are connected together forrotation in opposite directions to reciprocate the mass, acounterbalance Weight mounted on each gear, said weights being of equalmass and the weights on the first pair of gears being ararnged to be inopposed relationship to the weights on the other pair of gears in aplane substantially normal to the path of reciprocation of the mass andto be in accumulative relationship with the weights on the other pair ofgears and opposed to the mass in a plane paralleling said path.

3. Apparatus of the character described comprising a support, a pair ofspaced parallel crankshafts rotatably mounted on the'support along apath lying between said crankshafts and approximately normal to a planepassing through the axes of said crankshafts, a mass mounted forreciprocation on the support, an eccentric on each crankshaft, crossheadways secured to the mass, a pair of crossheads slidable in the ways eachcarried by a different one of the eccentrics, a first pair of gearsmounted in spaced relationship on one of the crankshafts, each meshingwith one of a similar pair of gears mounted on the other crankshaftwhereby said crankshafts are connected together for rotation in oppositedirections to reciprocate the mass, a counterbalance weight mounted oneach gear, said weights being of equal mass and the weights on the firstpair of gears being arranged to be in opposed relationship to theWeights on the other pair of gears in a plane substantially normal tothe path of reciprocation of the mass and to be in accumulativerelationship with the weights on the other pair of gears and opposed tothe mass in a plane paralleling said path.

4. A punch press comprising a frame, a pair of spaced parallelcrankshafts rotatably mounted in the frame, a ram mounted forreciprocation on the frame along a path lying between said crankshaftsand approximately normal to a plane passing through the axes of saidcrankshafts, an eccentric on each crankshaft, crosshead ways secured tothe ram, a pair of crossheads slidable in the ways each carried by adifferent one of the'eccentrics, a first pair of gears mounted in spacedrelationship on one of the crankshafts, each meshing with one of asimilar pair of gears mounted on the other crankshaft whereby 11 i saidcrankshafts are connected together for" rotation in opposite directionsto reciprocate the ram, each of said gears having a lightened portion onthe same side .of the crankshaft as the eccentric to counterbalance theeccentrics and the crossheads, a counterbalance weight adjustablymounted on each gear, said weights being of equal mass and the weightson the first pair of gears being arranged to be in opposed relationshipto the weights on the other pair of gears in a plane substantiallynormal to the path of reciprocation of the ram and to be in accumulativerelationship with the weights on the other pair of gears and oposed tothe ram in a plane paralleling said path. 1

5. Apparatus for counterbalancing. a reciprocating mass comprising asupport for the reciprocating mass, a pair of spaced parallelcrankshafts rotatably mounted on the support and connected to-the rnassfor reciprocating the same along a path lying between said crankshaftsand approximately normal to a plane passing through the axes of saidcrankshafts, a plurality of counterbalance weights mounted on thesupport for rotation about axes substantially normal to and positionedon opposite sides of the path of reciprocation of the mass andsubstantially equidistant therefrom, said weights being distributedsymmetrically about a line coincident with the path of movement ofapproximately the center of the reciprocating mass, and means forrotating said weights at a speed equal to the rate of rotation of thegen . References Cited in the file of this patent v UNITED STATESPATENTS Re. 23,373

Oschwald June 5, 1951 630,229 Hoyt Aug. 1, 1899 1,205,895 Hoyt Nov. 21,1916 1,349,283 Kollack Aug. 10, 1920 1,494,547 Hubbard May 20, 19341,945,992 Boblett Feb. 6, 1934 1,959,602 Stanbon May 22, 1934 2,009,660Irmis July 30, 1935 2,094,349 Carlson Sept. 28, 1937 2,268,242 CandeeDec. 30, 1941 2,280,384 Dickson Apr. 21, 1942 2,283,504 Johnson May 19,1942 2,284,515 Criswell May 26, 1942 2,306,777 Buzonik Dec. 29, 19422,595,464 Kaufmann May 6, 1952 2,610,524 Maussnest Sept. 16, 19522,639,737 Forsberg May 26, 1953

